15 minutes heating

uncle-albert

I've got a relatively new Worcester Bosc combi boiler, just less than 5 years old and i put my heating on for 15 minutes this morning. Checked the smart meter before i switched on and it cost me £0.60 for 15 minutes. 

Robin9

That £0.60 includes your standing charge for the day

km1500

that will of course  Include the cost of bringing all the pipe work and metal radiator bits up to temperature

the next 15 minutes will be cheaper

uncle-albert

No i excluded the standing charge.

Brebal

I’ve been calculating mine too. It costs me 80p for an hour of heating. (Boiler is over ten years old I think). 

[Deleted User]

Depending on the size of your boiler, it will run at high power at start up. As the home starts to reach the set temperature, then boiler will modulate down to a lower output setting. The lowest setting for most 24kW boilers is about 7kW. If a smaller heat demand is required to maintain the set temperature, then the boiler will cycle on/off. 

This is my smart meter graph from a day in December last year. The bars represent the amount of gas (kWh) consumed in a 30 minute period. I am guessing here: the reason that the kWh figure is lower in the first 30 minutes is because the boiler return temperature will be very low. The lower the return temperature, the greater the boiler efficiency. As radiators heat up, the boiler return temperature will increase.

Brebal

[Deleted User] said:

Depending on the size of your boiler, it will run at high power at start up. As the home starts to reach the set temperature, then boiler will modulate down to a lower output setting. The lowest setting for most 24kW boilers is about 7kW. If a smaller heat demand is required to maintain the set temperature, then the boiler will cycle on/off. 

This is my smart meter graph from a day in December last year. The bars represent the amount of gas (kWh) consumed in a 30 minute period. I am guessing here: the reason that the kWh figure is lower in the first 30 minutes is because the boiler return temperature will be very low. The lower the return temperature, the greater the boiler efficiency. As radiators heat up, the boiler return temperature will increase.

Hmm so for me, if the thermostat is set to 16 and it drops in the night, the heating comes on for ten mins to get it back to 16.  As it gets colder that might happen multiple times in the night I guess. 

Would it be better to turn the heating off. Let it drop to few degrees during the night and then the heating come on in the morning. It’ll be on for longer to get it back up to 16 so that’s why I went with the first method. 

Astria

Meanwhile I've use 2.1 units in the last 7 days to keep the house at 18c, so 23.2 kWh, so £2.32 ?

inkydolphin

Brebal said:

Would it be better to turn the heating off. Let it drop to few degrees during the night and then the heating come on in the morning. It’ll be on for longer to get it back up to 16 so that’s why I went with the first method. 

I'm no expert in thermodynamics but my complete guess is it would probably end up being a similar cost.

BUFF

In theory the higher the temperature differential to outside the higher the heat loss so there should be a higher heat loss from maintaining 16C overnight (let us say 8hrs) compared to letting it drop overnight to say, 14C & reheating to 16C in the morning.
Whether it's actually measurable in a real house would depend upon size of installation &  having 2 absolutely identical test days (unlikely).

Brebal

BUFF said:

In theory the higher the temperature differential to outside the higher the heat loss so there should be a higher heat loss from maintaining 16C overnight (let us say 8hrs) compared to letting it drop overnight to say, 14C & reheating to 16C in the morning.
Whether it's actually measurable in a real house would depend upon size of installation &  having 2 absolutely identical test days (unlikely).

I’m going to have to try and test it as best I can I reckon. Seems daft to have the heating coming on when I’m tucked up in bed.